Michael wrote:
Aren't Matte Proofs used all the time here? The UNC versions of all
Commems are essentially Matte Proofs.

No. By definition, a proof coin must be (MUST be)
1. struck multiple times.

2. from specially prepared dies

3. on specially prepared planchets.

It is true that there are cases where proof dies were dragooned into
business strike usage. However, it is generally true that the
diagnostics for a proof coin have little to do with the frostiness,
etc., and everything to do with the DIE diagnostics. Proof coins are
struck from proof dies. Proof dies are (generally; most often; with
exceptions) NOT the same dies as the ones used for business strikes.

(Did you read the article I wrote on Proof Gold?)